The invention relates to a device for heating a motor vehicle, comprising a heat exchanger which is supplied with coolant from an engine and in the case of which a bypass is placed between the limbs of the heating circuit extending respectively downstream and upstream from the engine and the heating circuit includes a heat storage means.
Motor vehicle heating systems of this type have already been proposed. Since in the case of motor vehicle heating systems which receive their energy in the form of heat from the engine radiator water, the heating effect is only developed with a considerable time lag after starting up from cold, attempts are being made to arrange a heat storage means in the heating circuit so that it may be heated by the coolant and to arrange the heating circuit so as to bypass the engine when the coolant in the vicinity of the engine has not so far reached the required operating temperature so that after a cold start the heat of the heat storage means is transferred to the heating circuit and generally is imparted to the vehicle heating system.
So far considerations have been based on an arrangement in which the heat storage means is placed in a duct of the heating circuit bypassing the vehicle heating system. Although this does not involve any disadvantages for the transfer of heat from the heat storage means to the vehicle heating system, there is the undesired effect that the heat storage means is not able to be efficiently heated because at times the entire amount of coolant is not able to flow through the heat storage means. More especially in the case of vehicle heating systems with water regulation coolant is only able to be supplied to the heat storage means when the heating is effect is decreased by regulation. It is only when the heating is completely turned off that the heat storage means is fully included in the coolant circuit. Thus it may occur that the radiator of the engine will dissipate heat to the surroundings before the heat storage means is fully charged. It is more particularly the case of relatively short runs that there is thus the undesired effect that the heat storage means will not be completely charged and after starting up from cold will not be able to yield heat at the rate required for a rapid warm up of the interior of the motor vehicle.